Key plug assembly

ABSTRACT

This invention is embodied in a pin tumbler lock having a multiplicity of pin tumbler chambers. The pin chambers comprise two portions, an upper portion in the lock housing and a lower, normally aligned portion in the key plug. The key plug is rotatably mounted in the lock housing but is restrained from axial motion relative thereto. The key plug has a keyway axially extending therethrough. The rear end of the key plug is of partially circular cross-section having a substantially straight surface formed by the chord joining the two ends of the arc formed by the partially circular section. The straight surface is generally perpendicular to and bisected by the keyway. The rear end of the key plug has an annular recess in which a retainer is received. The retainer has a side opening defined by two inwardly extending lugs which coact with the straight surface of the key plug rear end to register the side opening with the keyway for all rotational positions of the key plug.

United States Patent [1 1 Schultz [75] Inventor:

[52] [1.8. Ci. 70/380 [51] Int. Cl E05b 9/00 [58} Field of Search 70/367, 379 R, 380,

[56] References Cited UNITED STATES PATENTS 2,014,233 9/1935 Keil 70/379 R X 2,877,638 3/1959 Muttart... 70/367 X 3,429,154 2/1969 Schwartz 70/375 2,948,140 8/1960 Etster 70/379 R X 2,580,026 12/1951 Jacobi..... 70/379 R X 2,012,996 9/1935 Jacobi 70/367 Primary Iixaminer-R0bert L. Wolfe Attorney-Lcslie H. Blair, Ramon D. Foltz, Thomas A. lislc et al.

[ June 19, 1973 [57] ABSTRACT This invention is embodied in a pin tumbler lock having a multiplicity of pin tumbler chambers. The pin chambers comprise two portions, an upper portion in the lock housing and a lower, normally aligned portion in the key plug. The key plug is rotatably mounted in the lock housing but is restrained from axial motion relative thereto. The key plug has a keyway axially extending therethrough. The rear end of the key plug is of partially circular cross-section having a substantially straight surface formed by the chord joining the two ends of the arc formed by the partially circular section. The straight surface is generally perpendicular to and bisected by the keyway. The rear end of the key plug has an annular recess in which a retainer is received. The retainer has a side opening defined by two inwardly extending lugs which coact with the straight surface of the key plug rear end to register the side opening with the keyway for all rotational positions of the key plug.

2 Claims, 4 Drawing Figures KEY PLUG ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to locks and more particularly to a novel key plug assembly.

2. Description of the Prior Art It is quite customary, when assembling a key plug in a lock, to utilize securing means on the rear end surface of the plug, the securing means retaining the plug in the lock and also generally retaining a cam or other bolt actuating member on the key plug for rotation therewith. In the prior art it has been customary to utilize a retaining disc or other retaining member which was attached to the key plug by means of screws threaded into openings in the rear end surface of the key plug. This method of retention is not totally satisfactory as the axial length of the key plug assembly is substantially increased thereby. Another disadvantage of the prior art occurred when the key plug rear end had a keyway therethrough and was reduced in size to receive a sleeve thereabout, leaving only a small area on the key plug rear end surface for receiving the retaining means.

SUMMARY OF THE INVENTION In accordance with the present invention, the disadvantages of the prior art have been overcome to the extent that a novel key plug retaining means is provided which requires no screws or other attachments on the key plug rear end surface and thus maintains the key plug axial length to a minimum. The present invention utilizes a key plug rear end having a partially circular circumference joined by a substantially flat surface which is generally perpendicular to and bisected by the keyway. Adjacent the rear end of the key plug an annular recess is provided for receiving a snap ring type of retainer. The retainer has a side opening defined by inwardly extending lugs which engage the flat surface and coact therewith to retain the side opening in alignment with the keyway for all rotational positions of the key plug.

An object of the present invention is to provide an improved key plug assembly.

A further object of the present invention is to provide a novel key plug assembly requiring no screws or other fastening devices on the key plug rear end surface.

Another object of the present invention is to provide a novel key plug retaining means which allows a key plug assembly of minimal axial length. 7

Other objects and advantages of the present invention will become apparent from the following detailed description taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a rear elevational view of a pin tumbler lock embodying the present invention.

FIG. 2 is a side cross sectional view ofa lock utilizing the present invention.

FIG. 3 is an exploded view of the key plug, bold actuation means and retaining means.

FIG. 4 is a partial cross sectional view of the key plug and sleeve of the lock of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a pin tumbler lock may be generally seen at 10. The lock 10 comprises a housing 12 which has an externally threaded portion 14 for mounting the lock in a door or the like as is well known in the art. The forward end of the housing 12 includes a flanged portion 16 for limiting the rearward axial movement of the lock 10 in the door.

In the embodiment illustrated, a key plug 20 is rotationally mounted in a key plug sleeve 22 which in turn is rotationally mounted in a housing bore 24. It is understood that the present invention is equally applicable to those locks wherein the key plug 20 is directly received in a housing bore 24. A keyway 26 extends axially through the key plug 20 and key plug sleeve 22. The key plug has a forward flange 28 which limits the rearward axial movement of the key plug 20 in the housing 12.

Following substantially conventional practice, the lock 10 is provided with a series of axially spaced pin tumbler chambers 30. Each pin tumbler chamber 30 comprises an upper portion 30a in the lock housing, a lower portion 30b in the key plug 20 and in the present embodiment, an intermediate portion 30c in the key plug sleeve 22. Each pin tumbler chamber 30 contains a multipiece pin tumbler 32 which upon insertion of a properly formed key 34 allows the key plug 20 to rotate relative to housing 12.

Sleeve 22 which substantially ciircumferentially surrounds the key plug 20 may serve a number of well known purposes such as providing a master key system as is explained in detail in U. S. Pat. No. 415,178.

At the rear of lock 10, a reduced diameter section 40 of key plug 20 protrudes from sleeve 22. The reduced diameter section 40 has a partially circular circumference 42 and a substantially flat surface 44 which joins the ends of the circular circumference. The substantially flat surface 44 is generally perpendicular to and bisected by the keyway 26. Adjacent the key plug rear end surface 46 is an annular recess 48 which is adapted to receive retaining means 50. The retaining means 50 is in the form of a modified snap ring having a side opening 52 defined by a pair of inwardly extending lugs 54. The inwardly extending lugs 54 are adapted to engage the flat surface 44 and coact therewith when the retaining means is assembled in the annular recess 48 to maintain the side opening 52 in alignment with the keyway 26 for all rotational positions of key plug 20.

Interposed the sleeve 22 and the annular recess 48, the key plug reduced diameter section 40 presents a surface 58 for receiving the bolt actuating cam 60. The bolt actuating cam 60 comprises an actuating cam -member 62 and a mounting flange 64. The mounting flange 64 has an axial aperture 66 therethrough for receiving the surface 58. The aperture 66 is formed substantially identically to the circumference of the key plug reduced diameter section 40 and is defined by a circular portion 67 and a flat portion 68 for rotationally fixing the bolt actuating cam to the key plug. The aperture defining flat portion .68 has an outwardly extending slot 70 therethrough for alignment with keyway 26.

In view of the above it may be seen that a simple retaining means 50 has been provided for axially retaining the keyplug 20 in the lock housing 12 and the bolt actuating cam 60 on the key plug 20. The retaining means 50, by not interfering with "the keyway 26, may be placed in a position whereby no axial extension of the lock 10 is required. The key plug rear end surface 46 is not required to support any retaining means and therefore may be reduced in size to accept any type of sleeve thereabout.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed:

I claim:

1. A lock comprising:

a lock housing having an axial bore therethrough;

a key plug having an axial keyway therethrough, said key plug rotationally mounted in said bore, a portion of said key plug protruding from the rear end of said bore, said protruding portion having a partially circular circumference with a substantially flat surface joining the ends of said partially circular circumference, said substantially flat surface generally perpendicular to and bisected by said keyway;

a snap ring retainer for restraining forward axial movement of said key plug in said bore received in an annular recess adjacent the rear end of said key plug, said retainer having a pair ofinwardly extending lugs defining a side opening therein, said lugs engaging said substantially flat surface and coacting therewith to align said side opening with said keyway for all rotational positions of said key plug; and

a bolt actuating member, said member having an aperture therethrough for receiving said key plug protruding portion, said aperture partially defined by a generally straight edge having a slot extending outwardly therefrom, said slot generally perpendicular to and bisecting said straight edge, said straight edge engaging said generally flat surface and coacting therewith to rotationally fix said member to said key plug and to align said slot with said keyway for all rotational positions of said key plug.

2. The lock of claim 1 wherein said member is interposed and restrained from axial movement by said housing and said retaining means. 

1. A lock comprising: a lock housing having an axial bore therethrough; a key plug having an axial keyway therethrough, said key plug rotationally mounted in said bore, a portion of said key plug protruding from the rear end of said bore, said protruding portion having a partially circular circumference with a substantially flat surface joining the ends of said partially circular circumference, said substantially flat surface generally perpendicular to and bisected by said keyway; a snap ring retainer for restraining forward axial movement of said key plug in said bore received in an annular recess adjacent the rear end of said key plug, said retainer having a pair of inwardly extending lugs defining a side opening therein, said lugs engaging said substantially flat surface and coacting therewith to align said side opening with said keyway for all rotational positions of said key plug; and a bolt actuating member, said member having an aperture therethrough for receiving said key plug protruding portion, said aperture partially defined by a generally straight edge having a slot extending outwardly therefrom, said slot generally perpendicular to and bisecting said straight edge, said straight edge engaging said generally flat surface and coacting therewith to rotationally fix said member to said key plug and to align said slot with said keyway for all rotational positions of said key plug.
 2. The lock of claim 1 wherein said member is interposed and restrained from axial movement by said housing and said retaining means. 